Sir David Higgins, who takes over as chairman of HS2 Ltd on January 1, believes the new line can transform the UK economy, allowing companies to cut costs by moving out of Lonon.

But he warned that “absolutely everything” depended on a political consensus and said that opposition to such a large-scale infrastructure project would be disastrous.

“It is such an important programme - it cannot be divisive,” he told The Daily Telegraph.

“It is such a big investment - it is a programme that will last 50 to 100 years. It is central to economic growth and it will affect a lot of people’s lives. It is something that cannot pass by one vote in parliament – it is too important for that. What’s more, it will last through the life of a number of parliaments and perhaps a change of administrations, so you cannot have chopping and changing.”

The 50,000-page HS2 bill was published earlier in December, but there are splits within the ranks of both the Conservatives and Labour over the project. Shadow chancellor Ed Balls has raised concerns about the mounting cost and warned that, if he was Chancellor, he would not sign a “blank cheque”.

Sir David, who is he outgoing chief executive of Network Rail, in January, has been asked by David Cameron to find ways of cutting the estimated £50bn budget. Large-scale rail projects are notorious for delays and cost overruns, as was seen with the high-speed rail line through the Channel Tunnel, which has received fewer passengers than envisaged and created billions of pounds in debt.

Sir David said he plans to report to the government and opposition by March on the status of the project, including its ability to relieve capacity across the network, its potential connectivity with other transport modes and its cost and timetable for completion.

“I will look at whether it can be done quicker and how realistic is the cost plan,” he said.

“We have to set out the case for why we are doing it, what are the benefits and then give confidence that it can be delivered within a realistic timetable… We have to make the case that it is an absolutely crucial national asset.”

Construction on HS2 could begin within months, with the first phase from London to Birmingham due to be completed by 2026 and further connections to Manchester and Leeds by 2033.

Sir David, an Australian who oversaw construction of the London 2012 Olympic Park, was brought in to replace the retiring HS2 chairman, Doug Oakervee, who was criticised for failing to make the case publicly for the project.

Speaking in Sydney earlier this month, Sir David pointed out “there have been no new rail lines built north of Watford for a hundred years”. He said the only two other countries in the world which were as dominated by their capital as Britain, Japan and France, have both built high speed rail networks.

“We just have to keep investing to keep up with demand,” he said.

“The idea that we can get away with eking out the existing [rail] assets is not realistic. The UK, with three times more density than Germany or France in terms of population, and a really dominant city like London, depends on mass transit to spread the wealth.”

Sir David said HS2 would boost economic growth and transform Britain’s business landscape by allowing companies to relocate from expensive premises in London.

“Business in the UK is so concentrated in London. Think about the FTSE companies that are based there or where you want to raise capital; political decision-making is very centred in London, but Japan and France were really the first countries to get into high speed rail because they realised how those cities [Tokyo and Paris] provide wealth to the rest of the economy.”

However, he acknowledged that building HS2 alone would not solve the nation’s transport problems and it would be crucial to improve connections between the new network and existing systems. He said a model was Holland, where “you land at the airport and you are connected to the rail to trams and to the bike network.”

“We need a transport system that is relevant to the twenty-first century. That provides opportunities for cities, so it will provide the cities of the north that are barely connected at the moment.

“We need to think about how that rail line can extend to other forms of transport so you get an integrated transport system. That has to be the big thing we are aiming for.”